Discovery indicates planets may be common in galaxy New world is the closest outside the solar system


SAN FRANCISCO -- The world's champion planet-finders have discovered another new world, one tantalizingly close to Earth's doorstep.

Two San Francisco State University astronomers and two of their colleagues found the planet orbiting a star called Gliese 876, 15 light-years away. It is far closer than any previously known planet outside Earth's solar system.

The discovery of an extrasolar world so close to our own, and orbiting such a low-mass star, implies the galaxy is even more packed with these planets than previously believed, said lead researcher Geoffrey Marcy of San Francisco State.

"It's by far the closest star around which any planet has been found," Marcy said Wednesday.

The previous closest-known extrasolar planet orbits a star about 35 light-years away. A light-year is 5.9 trillion miles, the distance light travels in one year.

"It's by far the faintest star around which a planet has been found," Marcy said, too faint to be seen with the naked eye.

The star's size is another hint that extrasolar planets may be common, Marcy said.

"Most of the stars in the galaxy are these little puny stars that are a 10th to a third the mass of our sun," he said. "It certainly tells us that low-mass stars can harbor planets, and so there may be many more planets in the galaxy."

It is the seventh planet found since 1995 by Marcy and his associates. Twelve such planets have been found by astronomers. The latest was detected using one of the two giant Keck Observatory telescopes atop Mauna Kea on the island of Hawaii.

Marcy's partners in the discovery are Paul Butler of the Anglo-Australian Observatory in Australia, Steve Vogt of the University of California at Santa Cruz and Debra Fischer of San Francisco State.

The planet is about 1.8 times as large as Jupiter, the biggest planet in our solar system, Marcy said.

Though Marcy and his associates have discovered seven planets, the quest hasn't gotten dull.

"It's what Paul Butler and I have devoted our lives to," Marcy said. "We don't have kids. This is what we're after in life. The main thing we like to do is to find more planets."

Astronomer Susan Terebey and colleagues at a private research firm in Pasadena, Calif., announced May 28 that they had used the Hubble Space Telescope to spot what might be an extrasolar planet escaping from a star system about 450 light-years from Earth.

Pub Date: 6/26/98

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